Drilling tool



Patented Dec. l5, 1942 y DRILLING TOOL Hugh W. sinon and `Thon-ias H. sinon,

Corsicana, Tex.

Application February 25,`1941, Serial No. 380,438

5 Claims. (c1. l25e-'63) This invention relates to a drilling tool.

An object of the invention is to provide a tool of the character described designed for releasing surface casing set in a well bore, although itis capable of general use for similar purposes.

In theV drilling of deep wells, surface casing is usually set, and cemented, in the upper end of the well` bore, said surface casing forming an anchorage for surface equipment used in carrying on thedrilling operations. This surface casing is usually of largek diameter, so that drilling operations may be carried on through it, and usually several hundred feet in length. It is usually cemented in place at the top and bottom, at least and sometimes is completely surrounded by cement.

When the wall is abandoned, it is customary to leave the surface casing in the well, due to the difficulty encountered in removing it and in such case the surface casing is lost.

It is one of the principal objects of the present invention to provide a drilling tool which will work alongside, and around, the surface casing so as to release it to the end that it may be withdrawn and recovered for use.

Another object of the invention is to provide a drilling tool embodying a drill of the impact, or percussion, type adapted to drill a bore alongside the stuck casing, in combination with a sleeve type drill adapted to work thereover to drill around the casing to be released.

With the above and other objects in View the invention has particular relation to certain novel features of construction, arrangement of parts and use, an example of which is given in this f is threaded to receive the lower end of the sinker bar 3 which is screwed thereto and attached to the upper end of the sinker bar are the jars l to which the lower` end of the operating line 5 is connected. This operation line will usually be a wire cable.

Welded to one side of the impact drill I there is a sleeve-shaped drill I which is of a suiiicient inside diameter to pass over the couplings, as 1, of theA surface casing 8 set in the upper end of the well bore and which is to be removed.

The upper and lower endsof the sleeve-like drill VIi are tapered, that is they converge from the percussion drill I as shown Vin Figure 3.

The-lower end of the drill 6 is serratedv forming the teeth 9. which are slightly belled so as toV readily pass, over the casing couplings 'I and the upper end ofthe drill 6 is beveled outwardly, as at I0, so that the sleeve-like drill 6 will not hang on the couplings as the drilling tool is moved upwardly.

.The inner and outer sides of the percussion drill I are provided with longitudinalgrooves II,

I2 to provide passageways for the water with which the bore I3, formed by said drill, is wholly or partly filled.

The drilling tool is operated by the cable-tool method, which is well known in the drilling art, that is it is alternately lifted and dropped so as to disintegrate the formation at the bottom of the bore by impact. In order to remove the earth left by the groove I2, a side cutter I4 is provided. It may be welded to the drill I, at the bottom of the groove I2, a selected distance over the lower end of said drill. It is of somewhat less thickness than the width of said groove I2. It is downwardly flared as shown in Figures 1 and 3 and terminates at its lower end in a cutting edge I5. As the drilling tool is reciprocated up and down by the twisted cable 5, the twisting of the cable will cause an oscillation of the drill about its vertical axis thus causing a lateral swinging movement of the side cutter I4 so that the earth formation left by the groove I2 will be removed. This is necessary so that the bore I3 will be of full gage to allow the lowering of a bailer into said bore.

As hereinabove stated, when the surface casing is set the upper end of the bore around it is filled with plastic cement which soon sets. Upon beginning the work of removing the surface casing, a tubular nipple as I6 is attached to the upper end of the casing 8 to serve as a temporary guide and the sleeve-like drill 6 is fitted thereover. The drill tool is then successively elevated and dropped and the hardened cement is gradually drilled away from around the casing and the percussion drill I at the same time forms the bore I3 alongside the casing. The bore thus formed as well as the space left around the casing are kept lled or partly lled with water and the cuttings from the edges 2 and 9 will collect in the bore I3 until the water therein becomes laden with said cuttings. It is vtherefore necessary, from time to time, to withdraw the drilling tool and to lower a bailer into the bore I3 to bail out the fluid and cuttings therein and the bore is again supplied with clean fluid and drilling proceeded with as before until the surface casing is released.

When the surface casing has been drilled around throughout its length, it may then be readily pulled from the well bore by conventional equipment provided for that purpose.

If, for any reason, the surface casing cannot be drilled loose throughout itslength, or if itsV i.

lower end cannot be released from the cement in which it is imbedded, a charge .of dynamite may be lowered into the casing and xplodedin a well known manner so as toV shoot-off that portionof the surface casing which has been drilled around and the released portion then withdrawn from the well;

The drawing and description are illustrative merely while the broad principle of the invention will be defined by the appended claims.

What we claim is:

1. A drilling tool comprising a pair of ,drills secured together in side by side relation' and one of which is tubular and the other being solid; j

2. A percussion drilling tool comprising apair proximately parallel, one of said drills being tubular and having its ends flared.

3. A drilling tool comprising a pair of drills secured together with their axes in spaced relation and approximately parallel, one of said drills being tubular to operate over a well casing and having its ends flared, the operative ends of said drills being provided with cutters.

4. A drilling tool for drilling around a casing set in a well bore and comprising a pair of drills secured together with their axes approximately parallel, one of said drills being tubular to re- -ceive the casing therethrough and being shorter than the other drill and a side cutter on said other drill whose operative end terminates in a cutting edge.

5. A drilling tool for drilling around a casing set in a well boire and comprising a tubular drill shaped vto t over a casing in a well bore and to operate against the formation around said casing, cutters on the lower end of the drill, a drill secured to the side of the tubular drill and having a cutter on its lower end, and being positioned to forma bore alongside the casing, the axes of said drills being approximately parallel, said drilling tool being of the percussion type and being effective to simultaneously disintegrate the formation immediately about the casing and to form a bore alongside the casing.

HUGH W. SITTON. THOMAS H. SIITON. 

